Improvement in postal cards



' UNITED TATES PATENT OFFICE.

HENRY M. JOHNSTON, OF NEW YORK, N. Y.

IMPROVEMENT IN POSTAL CARDS.

Specification forming part of Letters Patent No. 144,677, dated November18, 1873; application filed May 16, 1873.

To all whom it may concern:

Be it known that I, HENRY M. J OHNSTON, of the city, county, and Stateof New York,

I have made a new and useful Improvement in 7 tle force that it isreadily eifaced, so as to make such cards of much less value than theywould otherwise be. Now, the object of my invention is to prepare a cardor paper in the form of a postal card, so that when written on with ametallic pencil, as hereinafter described, the writing will beindelible, such writing being fully as permanent as if written with themost indelible ink.

The following description will enable any one skilled in the art to makeand use my invention.

I take paper or card-board of the proper quality used for themanufacture of postal cards and treat it in the following manner: Iweigh eighteen ounces of glue and soak it for about twenty-four hours insix pints of water. I then place the-vessel containing the soaked gluein a water-bath, and apply heat sufficient to dis solve the glue. I thenstrain the glue through a flannel strainer. (The kind of glue I preferto use for the purpose is that known as Coignets No.1 glue.) I then taketwenty-eight pounds of Kremnitz white in dense pulp and mix itintimately with nine pints of water, to which I then add the entireamount of glue solution as before prepared, and thoroughly mix the wholetogether. I then stain the mixture with any suitable coloring matter toimitate the color of the paper of which postal cards are now made; butthe staining of the mixture is not essential to my invention. I thenapply the mixture to the surface of the paper intended for the postalcards by means of brushes, either by hand or by machinery, in the samemanner as in the coating of cardboard or paper-hangings, and, after thecoating is dry, I then coat the reverse side of the paper with themixture in the same manner as before,

and allow it to dry. After drying, there is found upon the surface ofthe coating a film of very fine p articles, which have but littleadhesion to the body of the coating. This film I remove, exerting agentle friction upon the coating with a soft brush or other suitablefriction-surface.

I then pass the paper or card-board between highly-polishedcalendering-rolls under press ure sufficient to smooth its surface andimpart to it a highly lustrous finish, or I take the postal cards (asfurnished and issued by the Post- Office Department) and I coat theentire side which is designated by the Department for the message withthe mixture by use of brushes in the same manner as in coating thepaper, and I allow the card so coated to dry. After drying, the cardsare laid upon a flat surface, with the side uppermost which is intendedfor the address. I then make use of a stencil-plate so cut that, whenlaid upon the card, it will cover its entire surface, except that partwhich the address is intended to be written upon, and,

having placed the plate upon the card, I then brush the mixture'upon theuncovered part, and then remove the plate and allow the mixture to dry.The card so coated I then brush and calender in precisely the samemanner as described for the paper.

I then prepare a solution of salts, in the proportions and in the manneras follows: Commercial sulphate of alumina, eleven ounces; chloride ofammonium, eight ounces; chloride of sodium, eight ounces; biborate ofsoda, four ounces; water, two gallons.

To make the solution of the foregoing salts,

I take a porcelain-lined kettle and put into it the sulphate of aluminaand half of the water,

and then place the kettle over a fire and heat the water nearly to theboilin g-point, and, after the sulphate is dissolved, I add and dissolvethe chloride of ammonium by occasional stirring. I then add the chlorideof sodium, and, when dissolved, I add the biborate of soda, and stir thesolution until the last-named salt is completely dissolved, and thesolution becomes clear. I then remove the kettle from the fire and addthe remaining gallon of water, and allow the solution to get cold andall-extraneous matter to settle to the bottom. I then decant the clearsolution into a wooden trough, and in it I immerse the coated paper orpostal card which I have described, and I subject it to the action ofthe solution for a period of time varying from half a minute to aminute. I'then remove the paper or card from the solution and pass itthrough water, so as to remove the superfluous solution of salts andprevent any crystallization of the salts on the surface of the coatedpaper or card, and then allow it to dry. I then pass the paper or cardthrough calen-V dering-rolls for the purpose of fiattenin g it. Thepaper may then have the Government postal stamp and other approvedmatter pressed or printed upon it.

I do not limit myself to the compounds named, as they may be greatlyvaried by an expert chemist. There is a chemical action between thecompounds upon the surface'of the paper and that portion of the metallicpencil left upon it by the writing, which, at the same time, brings outthe color of the writing and fixes it v indelibly upon the card. Infact, it is one of the most permanent kinds of writing known, as it maybe wet and a great amount of friction brought, to bear upon it withoutinjury, Whereas the same amount of friction, if brought to bear uponwriting done with the best ink upongood paper, would entirely obliterateit and destroy the paper. The card may also be writ-- ten upon with penand ink, and although, when wet,"the surface writing or ink may bewashed away, as on writingpaper, yet the writing thereby onlybecomespaler, and that remaining will befound to be much more permanent anddurable than if written on the best writing-paper; but, vby the use ofmy invention, ink may be wholly dispensed with in writing on postalcards, and their value greatly increased. As a general rule such cardsare employed in sending hasty messages, which are frequently dispatchedat times and places where it is difficult or impossible to obtain penand ink. The metallic pencil may be carried in the pocket, and ready atall times for use.

Having described my invention, what I claim, and desire to secure byLetters Patent, is-

A postal card covered with the compounds herein described, or theirequivalents, so that a mark or writing with a metallic pencil will bepermanently fixed, as set forth.

HENRY M. JOHNSTON.

WVitnesses H. N. ELDREDGE, HENRY G. FORBES.

